How do I replace non-printable characters in a file?

To replace a non-printable character, you have to first determine the ASCII value for the character. You can use the “:ascii” ex command or the “ga” normal-mode command to display the ASCII value of the character under the cursor. You can enter the non-printable character by entering CTRL-V followed by the decimal number 1-255 (with no leading zero), or by x and a hex number 00-FF, or by an octal number 0-0377 (with leading zero), or by u and a hex number 0-FFFF, or by U and a hex number 0-7FFFFFFF Another alternative is to use the “:digraphs” ex command to display the digraphs for all characters, together with their value in decimal and alpha. You can enter a non-printable character by entering CTRL-K followed by two alphanumeric characters (a digraph).